Derivative Financial Instruments (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative [Line Items]
Derivative, Notional Amount	$ 200,000		$ 200,000
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	2,765	$ 62	22,320	$ 2,043
Other Contract [Member] | Other Nonoperating Income (Expense) [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 4,432	$ 0	$ 26,836	$ 0